Most people are still using Claude Code like a fancy autocomplete. Meanwhile, Anthropic just shipped what I think is the biggest upgrade since launch — and almost nobody is talking about it. Skills aren't instructions anymore. They're programs. Here's what dropped: 🔧 SKILLS SYSTEM (merged with Commands) - Custom slash commands and skills are now the same thing - Every skill gets a SKILL.md file with YAML frontmatter — description, tool restrictions, model routing, execution isolation - Claude auto-loads the right skill based on what you're doing. No manual switching. - Skills are directories now — templates, examples, validation scripts, all bundled together 4 built-in skills ship out of the box: - /simplify — spawns 3 parallel review agents to clean your code - /batch — decomposes large changes into 5-30 independent units, each gets its own agent + PR - /debug — reads debug logs and troubleshoots your session - /loop — runs prompts on a cron schedule ("check if deploy finished every 5 min") 🤖 SUBAGENTS (Specialized Workers) - Dedicated AI workers with their own context window, system prompt, and tool restrictions - Route simple tasks to Haiku (cheap), complex ones to Opus (smart). Per-skill, per-agent. - 5 built-in: Explore (read-only search), Plan (research), General-purpose, Bash, and Claude Code Guide - Custom subagents defined in markdown — store at project or personal level 👥 AGENT TEAMS (Experimental) - Multiple Claude Code instances working together with shared task lists - Teammates message each other directly — not just reporting back to a main agent - Best for: cross-layer changes (frontend + backend + tests), competing debugging hypotheses, research from multiple angles ⚡ HOOKS (17 Event Types) - User-defined handlers that fire at lifecycle points: SessionStart, PreToolUse, PostToolUse, SubagentStart, PreCompact, etc. - Three types: shell commands, HTTP endpoints, or LLM prompts - Can block dangerous operations before they execute